Efficient Simulation of Flow in Hydraulically Fractured Wells in Fractured Reservoirs Using Embedded Discrete Fracture Method

Abstract:

Presence of natural fractures distributed in sub-surface geological formations often have a large impact on flow during hydrocarbon extraction or energy extraction from geothermal systems. The flow mechanisms are further complicated in unconventional reservoirs by the creation of hydraulic fractures and their interactions with preexisting natural fractures. Reliable recovery prediction from such reservoirs is complicated by uncertainties in the distributions of natural fractures and challenges in accurate and efficient numerical simulation of recovery process. Embedded Discrete Fracture Modeling (EDFM) method is used in this study to enable faster numerical simulations by creating non-neighbor connections between grid-blocks intersected by one or more fractures. Multiple, equally probable realizations of Discrete fracture networks (DFN) are considered. EDFM method was used to capture intersections between natural fractures, hydraulic fractures and wellbore and calculate non-neighbor connections in the transmissibility matrix for efficient simulations. EDFM enabled simulations could be run orders of magnitude faster, compared to conventional simulations with necessary grid-refinement, with comparable accuracy of predictions. Simulation workflow with EDFM facilitated capturing the impact of uncertainty in the distribution of natural fractures on the predicted recovery. The proposed workflow allows rapid sensitivity analysis and optimization of well and hydraulic fracture spacing to minimize frac-hits in the presence of natural fracture networks. In addition to hydrocarbon extraction, the workflow has applications in energy extraction from geothermal systems.